Instrument for implanting sensors and solid materials in a subcutaneous location and method thereof

ABSTRACT

An implantation instrument for implanting a substantially solid material, including solid medication or drugs, in a subcutaneous location and method are described. An incising shaft includes a beveled tip with a cutting edge along a distal end. A syringe body is affixed to a proximal end of the incising shaft. The syringe body and the incising shaft each define a substantially non-circular hollow bore extending continuously along a shared longitudinal axis. The incising shaft bore does not exceed the syringe body bore in girth. Both the incising shaft bore and the syringe body bore are sized to receive the solid material. A plunger is conformably shaped to the syringe body bore and has an end piece facilitating deployment of the plunger assembly. The plunger slidably fits within the syringe body bore and advances the solid material through the syringe body bore and the incising shaft bore into the subcutaneous location.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 10/222,719, filed Aug. 15, 2002, pending; which is acontinuation of U.S. Pat. No. 6,436,068, issued Aug. 20, 2002, thepriority dates of which are claimed and the disclosures of which areincorporated by reference.

FIELD OF THE INVENTION

The present invention relates in general to subcutaneous implantationinstruments and methods and, in particular, to an instrument forimplanting sensors and solid materials in a subcutaneous location andmethod thereof.

BACKGROUND OF THE INVENTION

A major part of health care assessment involves the review and analysisof physiological measurements collected and recorded by electronic datasensors. In addition to vital signs, physiological measures can includedetailed measurements of organ functions, body fluid chemistry andrates, activity levels, and similar measures, both measured directly andderived.

The type and quality of physiological measures depends greatly on thetype and location of the sensor employed. External sensors, such asthermometers, blood pressure cuffs, heart rate monitors, and the like,constitute the most common, and least invasive, form of sensors.However, these sensors are extremely limited in the kinds of informationwhich they are able to collect and encumber the patient with wearing andmaintaining an external sensor. On the other extreme, implantable insitu sensors provide the most accurate and continuous data streamthrough immediate proximity to organs and tissue of interest. However,implantable sensors are invasive and generally require surgery forimplantation.

Recent advances in microchip technology have created a new generation ofhighly integrated, implantable sensors. For instance, PCT ApplicationNos. PCT/GB99/02389, to Habib et al., filed Jul. 22, 1998, pending, andPCT/GB99/02393, to Habib et al., filed Jul. 22, 1998, pending,respectively describe an implantable sensor chip and treatment regiment,the disclosures of which are incorporated herein by reference. Thesensor chip is adapted to receive and rectify incoming electromagneticsignals and to transmit data relating to treatment parameters bywireless telemetry to a receiver external to a body. Similarly, theemerging Bluetooth wireless communication standard, described athttp://www.bluetooth.com/developer/specification/specification.asp,proposes a low cost, small form factor solution to short range datacommunications, potentially suitable for use in implantable sensortechnology.

Even though implantable sensor technology is trending towards smallerand more specialized microchip sensors, in humans, these sensors muststill be implanted via surgical procedure. Minimally invasiveimplantation using large bore needles is impracticable because sensors,particularly when embodied using microchip technology, favor a prismaticshape with substantially rectangular cross sections. A large bore needlecan cause a core of flesh or skin (or hide, when used in domesticatedanimals) to form in the pointed tip as the needle is inserted.Cylindrical needles also severely limit solid sensor sizes, shapes anddimensions to only those that can be inserted through a circular bore.

Although current surgical approaches attempt to minimize the size ofincision and decree of invasion, implantation is, at best, costly,time-consuming, traumatic, requires multiple instruments and maneuvers,and potentially risky to the patient. Subcutaneous implantable sensorsoffer the best compromise between in situ sensors and external sensorsand are potentially insertable with a simple injection. These sensorsare typically implanted below the dermis in the layer of subcutaneousfat. The subcutaneous implantation of solid materials has been describedin the prior art as follows.

An insertion and tunneling tool for a subcutaneous wire patch electrodeis described in U.S. Pat. No. 5,300,106, to Dahl et al., issued Apr. 5,1994. The tunneling tool includes a stylet and a peel-away sheath. Thetunneling tool is inserted into an incision and the stylet is withdrawnonce the tunneling tool reaches a desired position. An electrode segmentis inserted into the subcutaneous tunnel and the peel-away sheath isremoved. Although providing a tool for subcutaneous implantation, theDahl device requires an incision into the subcutaneous fat layer andforms an implantation site larger than the minimum sized required by theelectrode segment. Further more, the cylindrical bore precludes theinjection of non-conforming solid sensors or materials.

An implant system for animal identification that includes a device forimplanting an identification pellet in a fat layer beneath the hide orskin of an animal is described in U.S. Pat. No. 4,909,250, to Smith,issued Mar. 20, 1990. The device includes a curved needle-like tube thatterminates at a tapered, sharpened point. An elongated, flexible plungeris slidably received within the needle-like tube. The pointed tip isinserted through the hide or skin and the plunger is actuated to drivethe identification pellet from the tip into the fat layer. However, theSmith device uses an oversized open bore which can cause coring of thehide or flesh.

A trocar for inserting implants is described in PCT Application No.PCT/US99/08353, to Clarke et al., filed Oct. 29, 1999, pending. Animplant retention trocar includes a cannula for puncturing the skin ofan animal and an obturator for delivering the implant. A spring elementreceived within the cannula prevents an implant from falling out duringthe implant process. The cannula has a distal tip design which causes aminimum of trauma and tearing of tissue during implant insertion.However, the distal tip design is specifically directed to cannulashaving a substantially circular bore and thereby limits the size andshape of implant which can be inserted through the Clarke trocar.

An instrument for injecting implants through animal hide is described inU.S. Pat. No. 5,304,119, to Balaban et al., issued Apr. 19, 1994. Theinstrument includes an injector having a tubular body divided into twoadjacent segments with a hollow interior bore. A pair of laterallyadjacent tines extend longitudinally from the first segment to thedistal end of the tubular body. A plunger rod has an exterior diameterjust slightly larger than the interior diameter of the tubular body.With the second segment inserted beneath the animal hide, the push rodis advanced longitudinally through the tubular body, thereby pushing theimplant through the bore. As the implant and rod pass through the secondsegment, the tines are forced radially away from each other, therebydilating or expanding the incision, and facilitating implant. Theinstrument is removed from the incision following implantation. Thoughavoiding the coring of animal hide or flesh, the instrument forms animplantation site larger than the minimum sized required by the implantand causes potentially damaging compaction of the implant against thelaterally adjacent times during implant delivery.

Therefore, there is need for a non-surgical instrument and method forsubcutaneous implantation of sensors and solid materials that preferablydoes not require an incision preparatory to instrument insertion.

There is a further need for a subcutaneous implantation instrument andmethod capable of implanting sensors and other solid materials that arenot readily disposed to implantation through a substantially circularbore.

Moreover, there is a further need for a subcutaneous implantationinstrument and method which is minimally invasive, preferably creatingthe smallest needed implantation site, and capable of implantationwithout exposing the implant to longitudinal stresses.

SUMMARY OF THE INVENTION

The present invention provides an implantation instrument and method ofuse for implanting sensors and other solid materials in a subcutaneousor other site. As used herein, “subcutaneous” refers generally to thoseimplantation sites located within a body below the skin. Theimplantation instrument consists of an incising shaft attached to asyringe body. The syringe body and incising shaft both define asubstantially non-circular hollow bore for accommodating the sensor orsolid material. The subcutaneous site is formed by a cutting edge on thedistal end of the incising shaft. The subcutaneous site can be clearedusing a clearing trocar slidably received within the hollow bore. Thesensor or solid material is advanced through the hollow bore anddelivered into the subcutaneous site. The depth of the subcutaneous sitecan be limited using a penetration limiting mechanism.

An embodiment of the present invention is an implantation instrument forimplanting a substantially solid material in a subcutaneous bodylocation. An incising shaft defines a substantially non-circular hollowbore extending continuously along a longitudinal axis. The incisingshaft has a beveled tip forming a cutting edge on a distal end thereofand is sized to receive a substantially solid material for implant. Thesolid material, which can include a sensor, is preferably protectedagainst damage by encasement within, for example, a mannitol pellet orsimilar carrier. The solid material can also be encased in titanium,silicone, epoxy, or other similar, functionally inert protectivematerial. A delivery mechanism receives the incising shaft and includesa pushing device facilitating deployment of the substantially solidmaterial through the incising shaft bore and into an implantation site.

A further embodiment of the present invention is a subcutaneousimplantation instrument for implanting a substantially solid material.An incising body includes a syringe body and an incising shaft. Thesyringe body and the incising shaft each define a substantiallynon-circular hollow bore extending continuously along a sharedlongitudinal axis. The incising shaft includes a beveled tip with acutting edge on a distal end. Several prismatic or non-cylindrical boreshapes are possible. The incising shaft bore and the syringe body boreboth are sized to receive the solid material. A delivery assemblyincludes a plunger slidably fitted within the syringe body bore. Theplunger is conformably shaped to the syringe body bore with an end piecefacilitating deployment of the substantially solid material into animplantation site.

A still further embodiment of the present invention is an implantationinstrument for implanting a substantially solid material in asubcutaneous location. An incising shaft includes a beveled tip with acutting edge along a distal end thereof. A syringe body is affixed to aproximal end of the incising shaft. The syringe body and the incisingshaft each define a substantially non-circular hollow bore extendingcontinuously along a shared longitudinal axis. The incising shaft boredoes not exceed the syringe body bore in girth. Both the incising shaftbore and the syringe body bore are sized to receive the solid material.A plunger is conformably shaped to the syringe body bore and has an endpiece facilitating deployment of the plunger assembly, the plungerslidably fits within the syringe body bore and advances the solidmaterial through the syringe body bore and the incising shaft bore intothe subcutaneous location.

A still further embodiment of the present invention is a method forimplanting a substantially solid material in a subcutaneous location. Abeveled tip of an incising shaft with a cutting edge along a distal endthereof is inserted into an implantation site. A proximal end of theincising shaft is affixed to a distal end of a syringe body. The syringebody and the incising shaft each define a substantially non-circularhollow bore extending continuously along a shared longitudinal axis. Theincising shaft bore do not exceed the syringe body bore in girth. Boththe incising shaft bore and the syringe body bore are sized to receivethe solid material. The solid material is advanced through the syringebody bore and the incising shaft bore into the subcutaneous locationthrough deployment of a plunger conformably shaped to the syringe bodybore. The deployment is effected via actuation of an end piece on adistal end of the plunger. The plunger slidably fits within the syringebody bore.

Still other embodiments of the present invention will become readilyapparent to those skilled in the art from the following detaileddescription, wherein is described embodiments of the invention by way ofillustrating the best mode contemplated for carrying out the invention.As will be realized, the invention is capable of other and differentembodiments and its several details are capable of modifications invarious obvious respects, all without departing from the spirit and thescope of the present invention. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an instrument for implanting sensors orsolid materials in a subcutaneous or other tissue location in accordancewith the present invention;

FIG. 2A is a longitudinal cross-sectional view of the implantationinstrument with a straight incising shaft;

FIG. 2B is a longitudinal cross-sectional view of the implantationinstrument with a curved incising shaft;

FIG. 3 is a diagrammatic view illustrating the implantation of a sensoror solid material into a subcutaneous site;

FIG. 4A is a diagrammatic view illustrating the clearing of asubcutaneous site using the implantation instrument fitted with aclearing trocar in accordance with a further embodiment;

FIG. 4B is a diagrammatic view illustrating the subcutaneousimplantation of a sensor using the implantation instrument fitted with apushing stylet in accordance with a further embodiment;

FIGS. 5A-D are transverse cross-sectional views of the implantationinstrument illustrating, by way of example, various bore configurations;

FIG. 6 is a segmented side view of a clearing trocar;

FIG. 7 is a segmented side view of a pushing stylet; and

FIGS. 8A-8B are section views illustrating penetration limitingmechanisms for use with the implantation instrument; and

FIG. 9 is a perspective view of an instrument for implanting sensors orsolid materials in a subcutaneous or other tissue location in accordancewith a further embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of an instrument 10 for implanting sensorsor solid materials in a subcutaneous or other tissue location inaccordance with the present invention. The implantation instrument 10consists of two principal groups of components, an incising bodyconsisting of an incising shaft 11 and a syringe body 15, and a deliveryassembly consisting of a plunger assembly 20. The delivery assembly isreceived into the syringe body bore by sliding the plunger assembly 20through proximal bore opening 19.

The incising shaft 11 is formed with a beveled and rounded tip 12 thattapers into a surgically sharp cutting edge 13 formed on a distal edge.The beveled tip 12 includes a distal bore opening 14 through which thesensor or solid material is delivered into the implantation site.

In the described embodiment, the sensor or solid material (implant) hasapproximate dimensions of 5 mm by 10 mm by 20 mm. The critical dimensionis the cross-sectional profile, that is, the height and width, of theimplant which must conform to passage through the syringe body andincising shaft bores. Other non-linear, prismatic shapes are equallyusable provided the implant can fit within the confines of the syringebody and incising shaft bores. The implant could also be folded orcompacted to minimize the cross-sectional profile with the implantunfolding or expanding upon implantation. As well, the implant ispreferably protected against damage by encasement within, for example, amannitol pellet in the case of a solid drug delivery system or epoxy inthe case of an implantable sensor.

An implantable sensor microchip suitable for use in the presentinvention is described in PCT Application No. PCT/GB99/02389, to Habibet al., filed Jul. 22, 1998, pending, the disclosure of which isincorporated herein by reference. Such a sensor could be used formonitoring and collecting physiological or chemical measures. Similardevices for therapeutic uses, including treating cancer, and for healthcare giving, including administering solid medication in the form ofboluses, are possible. As well, the present invention has equalapplicability to implantation of sensors, including location andidentification sensors, and solid materials in domesticated animals. Thesensor could also constitute or include a data transmitter with which toexchange information and telemetered signals.

The incising shaft 11 is fixably attached to the syringe body 15 throughfrictional, adhesive, or preformed constructive means, as is known inthe art. Both the incising shaft 11 and syringe body 15 define asubstantially non-circular hollow bore extending continuously along ashared longitudinal axis, as further described below with reference toFIGS. 5A-D.

The plunger assembly includes a plunger 16, an interconnecting plungershaft 17 and a plunger end piece 18. The plunger 16 is conformablyshaped to fit within the syringe body bore. The plunger end piece 18facilitates deployment of the plunger assembly through the syringe bodybore and is preferably shaped to fit a thumb or palm impression.

In the described embodiment, the implantation instrument 10 is designedfor inexpensive and disposable use utilizing low-cost, sanitizablematerials. The incising shaft 11 can be fashioned from surgical gradestainless steel and has the approximate dimensions of approximately 10mm by 5 mm in cross section. The incising shaft 11 is approximately 50mm long and the length can be varied to accommodate differentimplantation depths. The plunger 16 is formed from plastic and rubberand preferably forms a watertight seal within the syringe body bore andhas the approximate dimensions of approximately 8 mm by 3 mm in crosssection. The plunger shaft 17 and plunger end piece 18 are formed fromplastic or similar material. Other materials, as would be recognized byone skilled in the art, could be substituted.

In a further embodiment, the syringe body 15 and plunger assembly can bereplaced by an automated injection system, such as used withimmunization injection guns or similar devices. These devices typicallyemploy compressed air or other inert gases to administer medication inlieu of manual plungers. Other automated variations includespring-loaded and similar mechanical injection systems. The incisingshaft 11 is fixably attached to the automated injection system whichfunctions as a delivery mechanism in place of the syringe body 15 andplunger assembly. Thus, the implant would be pushed through the incisingshaft bore using the compressed air or gas, or mechanical equivalent.

FIG. 2A is a longitudinal cross-sectional view of the implantationinstrument 10 with a straight incising shaft 11. The hollow bore definedby both the incising shaft 11 and the syringe body 15 runs along acommon shared axis. The incising shaft bore 22 is sized to allow theimplant to advance smoothly into the implantation site under the forwardlateral urging of the plunger assembly 20. The syringe body bore 23 mustbe at least as large as the incising shaft bore 22, but can be slightlylarger to accommodate lubricants, anesthetizing agents, or similarcoatings, such as mannitol, applied over the sensor or solid material.

The syringe body 15 preferably includes a circular collar 21, pair ofwinglets, ears, or eyelets, or similar structure, optionally formed on aproximal end of the syringe body 15 to assist a user in depressing theplunger assembly 20.

FIG. 2B is a longitudinal cross-sectional view of the implantationinstrument with a curved incising shaft 24. The curved incising shaft24, as well as the syringe body 15 and related components, are shapedinto a substantially continuous curve along the ventral side. Thecurvature helps regulate the penetration depth of the incising shaftand, in the described embodiment, has an arc of approximately 20degrees.

FIG. 3 is a diagrammatic view illustrating the implantation of a sensor28 or solid material into a subcutaneous site. Prior to delivery, thesensor 28 is fed through the proximal bore opening 19 of the syringebody 15 and then further advanced through the syringe body bore 23.During operation, the incising shaft 11 is inserted through the dermis25 and guided into the layer of subcutaneous fat 26, above the layer ofmuscle 27. The sensor 28 is then advanced through the incising shaftbore 22 by the plunger 16 into the subcutaneous site. Note that althoughthe foregoing view illustrates an implant into the subcutaneous fatlayer, one skilled in the art would appreciate that subcutaneousimplantation locations are not strictly limited to the subcutaneous fatlayer and are generally termed as those implantation locations situatedwithin a body under the skin.

FIG. 4A is a diagrammatic view illustrating the clearing of asubcutaneous site using the implantation instrument 10 fitted with aclearing trocar 29 in accordance with a further embodiment. The clearingtrocar 29, as further described below with reference to FIG. 6, ismounted to its own handle or plunger assembly and has a sharp cuttingtip 30 for optionally clearing a subcutaneous site prior to delivery ofthe implant.

Prior to implantation, the clearing trocar 29 is slidably received intothe syringe body 15 and is advanced until the cutting tip 30 is evenwith the proximal bore opening 19 of the incising shaft 11. Duringoperation, the incising shaft 11 and clearing trocar 29 are insertedthrough the dermis 25 and guided into the layer of subcutaneous fat 26,above the layer of muscle 27.

The cutting edge 13 of the beveled tip 12 makes an entry incisionthrough the dermis 25 and is laterally pushed into the subcutaneous fat26 until the cutting edge 13 is adjacent to the subcutaneous site. Theclearing trocar 29 is then urged through the subcutaneous fat 26 byadvancement of its handle or plunger assembly to prepare theimplantation site for delivery of the sensor 28 or solid material. Theclearing trocar 29 is then withdrawn from the subcutaneous site and outof the implantation instrument 10.

FIG. 4B is a diagrammatic view illustrating the subcutaneousimplantation of a sensor 28 using the implantation instrument 10 fittedwith a pushing stylet 31 in accordance with a further embodiment. Thepushing stylet 31, as further described below with reference to FIG. 7,has a blunt tip 32 for advancing the sensor 28 (or solid material)through the syringe body bore 23 and incising shaft bore 22 and into thesubcutaneous site. The cross section of the pushing stylet 31 closelyconforms to the incising shaft bore 22 while the plunger 16 closelyconforms to the syringe body bore 23. The pushing stylet 31 thus extendsthe reach of the plunger assembly 20 and allows the syringe body bore 23to have a different cross-section than the incising shaft bore 22.

The pushing stylet 31 is used while the incising shaft 11 is in situ inthe subcutaneous layer 26. Prior to delivery, the sensor 28 is fedthrough the proximal bore opening 19 of the syringe body 15 and furtheradvanced within the syringe body bore 23 by contact with the plunger 16.The pushing stylet 31 is slidably received into the syringe body 15 andis advanced until the blunt tip 32 contacts the sensor 28. Duringoperation, the sensor 28 is urged through the incising shaft bore 22 bythe pushing stylet 31 and into the subcutaneous site by advancement ofthe plunger assembly. Upon delivery of the sensor 28 into thesubcutaneous site, the incising shaft 11 and pushing stylet 31 arewithdrawn.

Although operation of the implantation instrument 10 is described withreference to the implantation of sensors or solid materials into asubcutaneous site situated within the layer of subcutaneous fat 26,implantations could also be effected in other subcutaneous,intramuscular, intraperitoneal, intrathoracic, intracranial, intrajoint,as well as other organ or non-subcutaneous sites, as would be recognizedby one skilled in the art. In addition, the foregoing procedure could bemodified to forego the use of the clearing trocar 29 for small sensors28 or solid materials. The clearing effect of the clearing trocar 29 canbe approximated by use of the incising shaft 11 alone whereby theincising shaft 11 is inserted into the subcutaneous site and thenwithdrawn by reverse deployment, thereby forming a slightly overwideimplantation site.

The operations of subcutaneous implantation can be carried out over aplurality of sites and with the same or different sensors 28 and solidmaterials. Similarly, several sensors 28 and solid materials could beimplanted at the same subcutaneous site during a single implantationoperation.

FIGS. 5A-D are transverse cross-sectional views of the implantationinstrument 10 illustrating, by way of example, various boreconfigurations. FIG. 5A illustrates an incising shaft 35 with asubstantially rectangular bore 36. FIG. 5B illustrates an incising shaft37 with a substantially square bore 38. FIG. 5C illustrates an incisingshaft 39 with a substantially oval bore 40. And FIG. 5D illustrates anincising shaft 41 with a substantially hexagonal bore 42. Note thecircumferential shape of the incising shaft need not follow the internalshape of the incising shaft bore. Other bore configurations, includingvariations on oval, rectangular, square, pentagonal, hexagonal,heptagonal, octagonal, and similar equilateral or non-equilateralshapes, are feasible.

In the described embodiment, the rectangular bore 36 has the dimensionsof approximately 10 mm by 5 mm. The syringe body bore 23 has a length ofapproximately 5 cm.

FIG. 6 is a segmented side view of a clearing trocar 45. The clearingtrocar 45 consists of a beveled tip 47 on the distal end of the clearingtrocar 45 and a clearing trocar shaft 46 affixed, either fixably orremovably, to the distal end of a plunger 16.

During a clearing operation, the clearing trocar 45 is fully extendedfrom the distal bore opening 14 of the incising shaft 11. The clearingtrocar shaft 46 is only long enough to clear out the subcutaneous site.The plunger 16 acts as a stop that limits the extent of penetration ofthe clearing trocar 45, thereby preventing the clearing trocar 29 fromincising too deeply into the subcutaneous fat 29. In addition, theclearing trocar 29 is sized to approximate the girth of the incisingshaft bore 22 and will clear a subcutaneous site only as wide asminimally necessary to facilitate implantation of the sensor or solidmaterial. In the described embodiment, the clearing trocar 45 has alength of approximately 2 cm beyond the tip of the syringe body 15.

FIG. 7 is a segmented side view of a pushing stylet 50. The pushingstylet 50 consists of a blunt tip 52 on the distal end of the pushingstylet 50 and a pushing stylet shaft 51 affixed, either fixably orremovably, to the distal end of a plunger 16.

During a delivery operation, the pushing stylet 50 is extended from thedistal bore opening 14 of the incising shaft 11. The pushing styletshaft 51 is only long enough to clear the distal bore opening 14. Theplunger 16 acts as a stop that limits the lateral travel of the pushingstylet 50. In the described embodiment, the pushing stylet 50 has anadditional length of approximately 2 cm beyond the tip of the syringebody 15.

FIGS. 8A-8B are section views illustrating penetration limitingmechanisms for use with the implantation instrument 10. The penetrationlimiting mechanisms limit the depth of penetration of the incising shaft11 and help prevent excessive penetration. FIG. 8A shows a fixedpenetration limiting mechanism consisting of a stopping flange 55attached to the incising shaft 11. The position of the stopping flange55 along the incising shaft 11 can be adjusted by loosening a hold-downscrew 58 and sliding the stopping flange 55 into the desired location.The lower edge of the stopping flange 55 has a bend 57 with an angle τ,preferably between approximately 30° and 60°, thereby forming an elbow56 which stops lateral travel upon contact with the skin.

FIG. 8B shows an adjustable penetration limiting mechanism consisting ofa stopping flange 60 attached a frictional collar 64. The stoppingflange 60 and frictional collar 64 are slidably attached to the incisingshaft 11. An adjustable collar 64, preferably in threaded communication65 with the frictional collar 64, manually stops deployment of thepenetration limiting mechanism by tightening the frictional collar 64against the incising shaft 11. The lower edge of the stopping flange 60has a bend 62 with an angle υ, preferably between approximately 30° and60°, thereby forming an elbow 61 which stops lateral travel upon contactwith the skin.

FIG. 9 is a perspective view of an instrument for implanting sensors orsolid materials in a subcutaneous or other tissue location in accordancewith a further embodiment of the present invention. The instrument isequipped with the stopping flange 55 shown in FIG. 8A. Other forms ofpenetration limiting mechanisms, both fixed and adjustable, could beused, as would be readily apparent to one skilled in the art.

While the invention has been particularly shown and described asreferenced to the embodiments thereof, those skilled in the art willunderstand that the foregoing and other changes in form and detail maybe made therein without departing from the spirit and scope of theinvention.

1. An implantation instrument for implanting a substantially solidmaterial in a subcutaneous body location, comprising: an incising shaftdefining a substantially non-circular hollow bore extending continuouslyalong a longitudinal axis with a beveled tip forming a cutting edge on adistal end thereof, the incising shaft bore being sized to receive asubstantially solid material for implant; and a delivery mechanismreceiving the incising shaft and comprising a pushing devicefacilitating deployment of the substantially solid material through theincising shaft bore and into an implantation site. 2-13. (canceled)